MS (Materials Science), the beamline to be completed in May 2018
Abstract
MS Source
Beamline Layout
Major Beamline specifications
Experimental Station
Contact Information
Acknowledgements
References
The SESAME Materials Science MS beamline for X-ray diffraction XRD applications is presently under construction. The beamline is based on donated components previously installed at the Swiss Light Source, but modifications in the beamline design have been introduced to match the characteristics of the SESAME storage ring. A wide range of XRD applications will be possible at the beamline (powder and single XRD studies). The commissioning of the beamline is expected to be in May 2018.
The MS source is 2 meter long wiggler W61 located along the I09 straight section. The main wiggler parameters are summarized in table 1 while these parameters were used to calculate the beamline flux spectrum (see figure 2). The minimum magnetic gap is 12 mm which have been decided based on the minimum vacuum chamber height available at SESAME (10 mm) during the first operation period. This magnetic gap will produce reasonably high flux up to 25 keV with about 6000 Watt of radiation power. Therefore the front end station; mainly fixed masks and filter; will deal with this high power in order to protect the optical components from damage. The flux distributions in the front end before and after the major front end components are shown in figure 3.
Figure 1 The MS wiggler source
Figure 2 The MS wiggler and its flux distribution at 12 mm magnetic gap (left) and the beam shape at wiggler centre (right)
Figure 3 flux distribution at the major components in the front end
Table 1 the main parameters of the MS wiggler source
| Overall W61 length (m) | 2 |
| Wiggler gap (mm) | 12 |
| Period length (mm) | 60.5 |
| Number of periods | 33 |
| Magnetic material | NdFe:B |
| Pole material | CoFe |
| Maximum field (T) | 1.38 |
| Deviation parameter K | 7.8 |
| Critical energy Ec (keV) | 5.8 |
| Total power @ 400mA (kW) | 6.01 |
Table 2 the location of the major beamline components from the wiggler centre
| Components | Distance (m) |
| Front end | |
| Wiggler W61 | 0 |
| Fixed mask I | 8.13 |
| Fixed mask II | 8.52 |
| Photon shutter | 8.92 |
| Bremsstrahlung stopper | 9.45 |
| Rotating filter (glassy carbon) | 10.39 |
| Horizontal slits | 10.9 |
| Vertical slits | 11.51 |
| Be windows | 13.57 |
| Optics | |
| Fast Absorber | 14.12 |
| Filters | 14.25 |
| Collimating Mirror | 15.58 |
| Wire Beam Position Monitor BPM | 16.68 |
| Double Si crystal Mono | 17.55 |
| Bremsstrahlung stopper | 18.44 |
| Focusing mirror | 20.01 |
| Photon shutter | 21.79 |
| Experimental | |
| Diffractometer (sample location) | 33 |
Figure 4 front-end and optics layout starting from left hand side, fixed masks (a), shutter (b), stopper (c), filter (d), vertical slits (e), horizontal slits (f), fast absorber (g), collimating mirror (h), monochromator (i), focusing mirror (j), photon shutter (k).
SHADOW3, through its last distribution ShadowOui was used to best optics performance in terms of flux, beam shape and energy resolution at the samples which are the major parameters of interests for XRD community. In order to provide an accurate ray-tracing simulation, not only geometrical factors were taken into account, but also physical factors like absorption/scattering of the initial photon beam by several optical elements were considered. In other words, taking into account the following properties:
- Absorption coefficient of Screens/Filters
- Reflectivity of Mirrors/Multilayers
- Diffraction profile of Crystals
- Slope errors of Mirrors
The beamline ray tracing analysis at 10 keV estimates the flux at the sample to be in the order of 1013 (photons/s), the energy resolution is about 2 eV and the effective beam size at the sample of 300 x 2800 μm2. Investigations of microstruture will be possible as the instrumental broadening, resulted from simulating the diffraction pattern for a standard material (see figure 6), is in the order of 0.01o at 15 keV.
Table 3: the major beamline specifications
| Energy range (keV) | 5 - 25 |
| Accepted divergence (m rad2) | 0.23 (V) x 1.5 (H) |
| Flux at the sample at 10 keV (photons/s) | 1.6 1013 |
| Energy resolution (eV) | 2 |
| Effective beam size at the sample (FWHM) (μm2) | 300 (v) x 2800 (h) |
Figure 5 calculated fluxes at the sample resulted from the ray tracing, the beam shape at the sample at 15 keV is shown on right up side.
Figure 6 the full width at half maximum of the simulated LaB6 XRD patterns at selected energies.
Diffractometer: (Information will be published soon)
Detector (Fast area PILATUS3 300K):
- Area: 83.8 x 106.5 mm2
- Pixel Size: 172 x 172 µ m2
- Time resolution (readout): 7 ms
- Framing rate: 500 Hz
- Weight (detector head): 7.5 Kg
Samples’ Stages and Environments: (Information will be published soon)
Contact Information
Mahmoud Abdellatief (Beamline responsible)
E mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
Phone: (+962-5) 351.13.48 Ext. 273
Fax: (+962-5) 351.14.23
The hard work of those who are involved in the design, constructions of the beamline at SESAME site is strongly appreciated.
We would like also to thank DECTRIS Company for offering a Pilatus 300K detector, especially Dr. Dubravka Sisak Jung for her efforts to the make this donation possible.
Special thanks go to Dr. Luca Rebuffi; who is an expert optics scientist at Elettra synchrotron; for his assistance on the beamline ray tracing calculations.
[1] M. Abdellatief, L. Rebuffi, H. Khosroabadi, M. Najdawi, T. Abu-Hanieh, M. Attal, and G. Paolucci, Powder Diffraction Journal, doi:10.1017/S0885715617000021
[2] Patterson, B.D., Abela, R., Auderset, H., Chen, Q., Fauth, F., Gozzo, F., Ingold, G., Kühne, H., Lange, M., Maden, D., Meister, D., Pattison, P., Schmidt, Th., Schmitt, B., Schulze-Briese, C., Shi, M., Stampanoni, M. & Willmott, P.R., 2004, Nucl. Instr. Meth. Phys. Res. B, 540, 42.
[3] Rebuffi, L. & Sanchez del Rio, M., 2016, J. Synchrotron Rad., doi:10.1107/S1600577516013837
